Then put the flap on and tightened it with the black nut. The nut can be really hard to get real tight. Getting it to click a few tines, requires some good force, and one of the little tabs that iDisk in there broke off when I tightened it too much.
So it flushes well, but I did reposition the chain and adjust its length a bit.
But I noticed after a little while that the toilet was adding water every few seconds. So I removed the assembly, removed and reapplied the new seal, and tightened the nut a few more turns. In fact it took a lot more tightening, but I'm at max point. I think it is holding water, but time will tell if it is slowly leaking.
So that's where I'm at. I assume I got the right part based upon similarity.
Hope this helps!